Iridium Communications says its next two launches of new-generation satellites will use refurbished SpaceX Falcon 9 first-stage boosters that have flown previously.

The announcement Thursday is another step in SpaceX's effort to reduce launch costs.

The company has launched a few used boosters and is trying to expand acceptance of reusability across the industry.

Hawthorne, California-based SpaceX has had successful landings of Falcon 9 first stages after launches from both coasts.

Iridium is in the midst of seven launches to replace its fleet that provides global mobile voice and .

The McLean, Virginia, company says insurers confirmed there is no increase in premiums for "flight-proven" rocket use.

Thirty new satellites are in orbit and the fourth launch is scheduled for Dec. 22 at Vandenberg Air Force Base, California.